Steam generator



July 13 1926. 1,592,509

R. A. THoM Er AL.

STEAM GENERATOR Filed Dec. 15, 1923 8 sheets-Sheet 1 V Zw "July 13 1926.1,592,509

R. A. THOM ET AL STEAM GENERATOR v i \O I 6 lI l Sli t K" n i n 5 U July13 1926.

R. A. THOM ET AL,

STEAM GENERATOR Filed Dec. 13. 1923 8 Sheets-Sheet 5 isi'siulmmlasiioliliiliiolmliolml 'we n o l w n v 4. e. /Nf

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July 13 1926.

R. A. THOM ET' AL STEAM GENERATOR Filed Dec. 15. 1923 8 Sheets-Sheet 5July 13,1926. 1,592,509

' R. A. THOM ET AL A STEAM GENERATOR FledDec. 13, 1925 8 SheetSfShBBt 6R. A. THOM ETI' AL STEAM GENERATOR Filed Dec. 15, 1925 gsheetglsheet vFIG. Z3.

July 13 ,1926. l

R. A. THo'M E-r AL STEAM GENERATOR 8 Sheets-Sheet B File@ ned. '1s 1925l, l IIJ Patented July 13'7 1926.

UNITED staresrarnur"OFFICE."v

.ROBERT ABsALoM THOM, or MANCHESTER, ENGLAND, AND Jar/ins Tiroir, orABERDEEN, SCOTLAND.

STEAM GENERATOR;

This invention has reference to steam generators and principally tosteam generators of the water-tube type:I the invention also relates toan improved water-tube equipment for theiire-bones or furnace chambersof railway locomotive and other boilers or steam generators, l'

While vthe invention has been designed primarily for use as or inconjunction with a railway locomotive boiler the inventionr is notrestricted to such boilers but is also applicable to steam generators'or boilers of other types and for various purposes;` for instance theinvention is applicable to marine boilers, road locomotive boilers,stationary boilers, portable engine boilers (for instanceboilers orsteam generators for operating the pumps of lire-engines), and toboilers or steam generators for operating air-craft propulsion engines.

The principal objects of the invention are to provide an improvedconstruction of water-tube boiler ror water-tube lire-box equipmentwhereby more effective and rapid heating of the water is obtained andgeneration of steam accelerated, the tubes forming the side Walls oftheiire-box being so formed and arranged as to permit expansion `andlcontraction without strain and consequent damage tothe joints of thesaid water tubes to the headers, distributors or collectors, andgenerally to improve the construction as a whole in order to providesimplicity, compactness and durability. In a boiler according to thisinvention the several water distributors or collectors are of simpleconstruction andare also such that the water tubes connected thereto maybe easily expanded into the holes provided to receive them, theVdistributors and collectors being also such as to provide the necessarystrength to withstand high workingvpressures without being unduly heavyor cumaersome. An important object of the present invention is toproduce or provide a steam generator which while being of minimum weightshall have a very high, or the maximum, steaming capacity.

In the case of a railway locomotive boiler with water-tube iire-boxequipment according to this invention the construction and arrangementof the parts are such thatvthe usual external configuration anddimensions Application filed December 13, 1823, Serial No.7'680,510, andin Great Britan'April 1i), 1923.

of the boiler barel and fire-box shell or casing can be maintained, theconstruction and arrangements being also such that the usual crown andside ystays of the fire-box are eliminated; further the back plate ofthe boiler at the' drivers cab can haveithe same profile as ina boilerof the present usual construction in which the lire-box has side waterspaces or chambers, so that the usual steam fittings onlthe back platecan be placed in the positions they usually occupy in the boilers nowgenerally in use. 'e

A water-tube boiler or a water-tube lirebox equipment according to thisinvention comprises, in combination, a water distributor or waterdistributing chamber arranged in communication with a water supplyvessel or chamber which, in the case of a locomotive type boiler, may bethe water space in the boiler barrel, and preferablyy (in the case of alocomotive lt-ype boiler) also in communication with the water spacebetween the inner and outer plates or walls at the fire-door orfire-hole end' ofthe tire-box, or

furnace chamber, a header or junction box or headers or junction boxesor the equivaf lent preferably located' at or near the bottom of thetire-box or furnace chamber, a water'collector or Water receiving drumor drums preferably situatedat a level above` the said water distributoror distributors,A

a plurality of downflow tubes situated at or adjacent each side of thelire-box or furnace `chamber and connecting,` the aforesaid waterdistributor or distributors with the aforesaid header or headers orjunction boxes, and aplurality of similarly situated up-ow tubesconnecting the said headers or junction boxes with the aforesaid drum ordrums. he said water vcollector or receiving drum or drums is or arepreferably ,arranged in con'imunication, forr instance, at one end,

`with the steam and water space of the boiler and also incon'ununication, for instance at the opposite end, with thecorresponding space between the inner and outer plates or walls at thefire-door or tire-hole end of thel lire-box or furnace chamber.`

Further according to this invention, in the preferred embodiment, theaforesaid downliow-wate'r tubes are arranged'as an outer row ofverticallydisposed tubes adjacent the plates constituting the side walls(ordinarily the shell or envelope) ot the tire-box or furnace chamber,each of the said downtlow tubes being of a suitably larger diameter orcross area than that oit the aforesaid up-'tlow tubes which are arrangedas an inner row or rows of vertically disposed tubes, the said inner andouter rows ot tubes at each side ot' the tire-box thus constituting theside walls of the tire-space within the tire-box, and the said rows oftubes and the 'toresaid water distributors and headers or junction boxesbeing located or accommodated in spaces corresponding or approximatelycorresponding to the usual water spacesl at each side ot' an ordinarytire-box ot a locomotive boiler.

A further feature ot' the water-tube boiler onlire-box equipmentaccording to this invention consists in the aforesaid downtlow tubesbeing of oval, elliptical or suitably iiattened torni in cross-section.whereby while obtaining the relatively large diameter or cross area otthese tubes they and their associated up-tlow tubes occupy a minimumspace in the lateral or transverse direction, and formy a practicallycontinuous water jacket at each side of the Afurnace chamber or tirespace Yin the lire-box. Further the construction and arrangements aresuch that in a space, for instance a nre-box, ot given dimensions arelatively large or the maximum number ot' water-tubes comprisingdown-flow and up-tlow tubes can be accommodated and further can beaccommodated in the small space available at each side o't the tire-boxot' a locomotive or other boiler.

rThe invention further consists in the combination ot the variousdevices or parts constituting the water-tube boilcrand its arrangementin the fire-box ot a. locomotive boiler. and in constructional detailsot certain of `the said devices or parts substantially as hereinafterdescribed with reference to the accompanying drawings and set forth inthe appended claims.

ln the accompanying drawings Fig. 1 is a` longitudinal vertical sectionof the tire-box and a portion ot the boiler barrel ot a locomotiveboiler or" the smoke or hre-tube type with water-tube boiler equipmentaccording to one embodiment of this invention applied thereto;

Fig. 2 is a cross-section, taken on the line 2.-2 in Fig. 1, andlooking` trom the right hand. Fig. 2 is a cross-section, taken on theline 2--2 in Fig. 1, and looking` from the lett hand. Fig. 3 is asectional plan view, taken on the line `s-3 in Fig. l.

3 is a seccional plan view, taken on the line .3a-3 in Fig. Q,

Figs. 4-17 are detail views showing the construction orp certain `aartsof the tire-box Vwater-tube equipment shown in Figs. 1 and 2 andhereinafter described. Fig. 17a is a. broken longitudinal sectionthrough one ot the water distributors 9 showing its communication withthe water spaces at the ends of the fire-box casing. Fig. 17" is asection on one end portion of the water receiving drum 8 showing itwelded in a hole in the end plate, and is drawn to a larger scale.

Figs. 18 and 19 are respectively front and side sectional elevations oiportions ot a locomotive lire-box showing a modilied constructionhereinafter described.

Fig. 2O is a detail view showing a torni or method ot construction o'l'the water distributors employed in the construction shown in Figs. 18and 19.

Fig. 21 is a view similar shows' a modification. Fig. 2Q is a viewsimilar to Fig. 2,- and Fig. 22a is a view similar to Fig. Qa. alsoshowing the said modification.

Figs. 23 and 9.1i are detail views, respectively a sectional pla-n anda. transverse section, ot one ot the headers or junction boxes shown inFigs. 21 and 22 but drawn to a larger scale.

Fig. 25 is a= Sectional elevation ot portion ot' a lire-box showing amodiiied construction hereinafter described.

Lilie reference numbers indicate like parts in the various figures ofthe drawings.

In the drawings, 1 is a portion ot the barrel ot a locomotive boiler ofthe usual smoke or tire-tube type, 2 being the boiler tubeplate at thetire-box end ot the barrel and 3, 3a the smoke-tubes ot the boiler, thesmoketubes 3 being theusual enlarged smoke-tubes` into. which U-shapedsuperheating pipes or steam superheater elements (not sh wn) extend. 4lis the back plate ot the boiler at the rear or lire-door end otthelire-box. and 5 respectively the rear and troni'I end plates of thetire-box, and (i are the plates forming the sides and top ot thelire-box casing or shell. Il is the iront end plate ot the .tire-boxeasing. The tire-box tubeplate Q as shown is a flanged or dishcd plate,the flanged portion ot which is .let into and secured to the forwardlyprojecting or flanged portion 5" of the inner plate 5a at the front endot the lire-box. Apertures 7 and 7 are formed respectively in the plate5 at the rear end ot the hre-box and in the inner plate 5 at the irontend of the tire-box. the inwardly turned portions or flanges 7b, 7c otthe said plates surrounding the said apertures and constituting socketswhich receive the ends ot the hereinbetorc mentioned water receivingdrinn or water collector 8 which in the example shown is cylindrical incross-section. its ends boing secured. for instance by riveting, to theto Fig. 1, but

As will be understood the usual inner side plates or side walls andcrown plates of the lire-box or 'furnace chamber proper as employed inthe usual hre-boxes ot locomotive boilers are omitted from a fire-box towhich a water-tube boiler equipment, according to this invention, 1sapplied.

9 arey the hereinbefore mentioned water rectangular form in crosssection, and are,

through their open ends, in free communica tion with the water space ofthe boiler their rear ends con'inninicating with the water space betweenthe plates 1 and 5, apertures being provided in the plate 5 at the rearend ofthe firebox and in the inner plate 5a at the frontend of thefire-box with which apertures the open ends of the said waterdistributors register. 10 are flanges provided on the ends ofthe waterdistributors 9 whereby they are secured respectively to the plate 5 atthe .rear end of the tire-box andto the inner plate 5a at the front endof theA tire-box, for instance,as shown, by being riveted to the saidplates. i*

11 are the hereinbefore mentioned headers or junction boxes situated ator adjacent to the bottom of the fire-box or furnace chamber andextending from front to rear thereof as shown in Figs. 1 and 2. 12 arethe hereinbefore mentioned down-flow or down-take water tubes ofrelatively large diameter or cross area, and 13 are the up-low tubes ofrelatively small diameter or cross area. As will be clearly seen inFigs. 2 and 3 of the drawings the down-flow tubes 12 are arranged as anouter row of tubes adjacent to the side plates orwall 6 ofthe fire-boxand the up-flow tubes 13 are arranged as an inner row of tubes, theupper portions of these tubes, in the example shown, being bent toconform approximately to the crosssectional contour of the fire-boxwalls or shell4v 6. The upper or .inlet'ends of the down-flow tubes12,'are, as shown, secured (inthis instance expanded in holes) in thebottom of the water distributors 9, 14 being screw plugs in holes in thevtop of these distributors for the linsertion of a tube-'expanding tool.The lower or outlet ends of the said down-flow tubes 12 are secured (inthis instance expanded in holes) in the top 'of the aforesaid headers orjunction boxes 11, openings 11a being provided in the bottom of theheader 11 for the insertion of the tube expanding tool and cover plates15 provided for closing the said openings these cover plates beingsecured to the bottom of the headers 1l by lmeans of studs and nuts orotherwise as may be found practicable. The

lowerv or inlet ends of the up-flow tubes 13 are also, asshown,fexpanded inholes inthe `top of the headers or junction boxes 11and the upper or outlet ends of the said tubes 13 are secured (inthisinstance expanded) in holes in the hereinbefore mentioned waterreceiving drum or water collector 8. As will be' seen the upiiow tubes13 in each rowof these tubes are arranged as close together aspracticable and in such manner 1in relation to the associated down-flowtubes 12, constituting the outer row, that opposite thespacebetweenadjacent tubes12 there ris a. tube .13 the arrangement beingtherefore such thatthey associated rows of inner yand outer water tubes12, 13, form practically continuous side walls of the tire-box orfurnace chamber proper, very little rlagging being required in thespaces between the rows of'tubes 12 and the side plates 6 forming theshell orouter wall'of the fire-box.

Further the inwardly bentupper portions 13 of the closely spacedwater-tubesvl, together with wrapper plates 16, located above these bentportions, and thelower portion of the drum 8 constitute the crown or topof the {ire-box or furnace chamber proper. As shown the wrapper plates16 extend from the `water receiving drum 8 to the water distributors 9and are secured for instance riveted) to brackets 17, 17a fixedrespectively to the side of the drum 8 and tothe side of the waterdistributors 9. f j According to thisinvention in the preferredembodiment thereof they aforesaid down-take or down-flow water tubes 12are of oval, elliptical or flattened form in cross-k section, as shownin Figs. 14, 15, 16 and 17 of the drawings,fwith circular end portions12a, 12b whereby the said tubes are expanded lin the water distributors9 and headers or junction boxes 11 as hereinbefore described. This formor construction of the tubes 12 enables ample bridge spaces to beprovided f between the holes in the water distributors 9 and in thejunction boxes 11 in -which the ends 12a, 12b of the said tubes areexpanded, while at the same time providing the necessary relativelylarge cross area of the tubes 12 and enabling these tubes and thetubes13 of the inner row at each side of the fire-box to be accommodated inthe same or approxif mately the same restricted space as that lwhichconstitutes the usual 'water space bevtween the youter plate 6 or shellof the firebox and the inner pla-te or side walls of the lire-box orfurnace chamber ,proper as provided inthe usual firebox of an ordinarylocomotive boiler. f

The aforesaid tubes 12 of oval elliptical or flattened cross-section canbe conveniently produced from solid drawnsteel tubes of circularcross-sectionk by taking a tube of larger diameter than that desired forthe end portions 12a, 12b and swaging down the ends of said tube tothedesired diameter for connection to the junction boxes 11 and waterdistributors 9, and by then pressing` down or flattening the main lengthof the tube between the swaged down ends 12a, 12" until the dimension ofthe tube in onedirection of its cross section corresponds to thediameter of the said swaged down ends, the dimension of the tube in theother direction of its cross-section being considerably increasct, andapproximately equal to the distance between centers of the tube holesQ() in the bottoni of the water distributors or feeders 9 and alsoapproximately equal to the distance between centers of the tube holes 21in the top of the junction boxes lil, the tube being thereafter bent tothe shape requise-rl, so that Vwhen in place the upper end portions ofthe tubes are set outwardly to conform or substantially conforin to theshape of the shell or outer plate struct-ure of the'lire-box.

yllhe hereinbe fore mentioned water distributors 9 may each be.conveniently formed of two pressings welded or otherwise suitablysecured together. Referring to Figs. el and 5 of the drawings, in oneinethod of constructing the water distributors 9 portions of steel plateeach of the required dimensions to forni one-half of the distributor arefirst. pressed into a U or channel shape (see Fig. 4;) and the endportions thereof are subsequently flanged in a suitable ilanging press,to produce the flanges 10. rl`he nieeting edges of the sides of the twoU-shape portions or halves of the distributor suitably chainfered orotherwise machinedV to provide a satisfactory bed for the metaldeposited in the operation of welding the two lll-shaped pressingstogether.

The junction boxes or headers 11 inay be formed by pressing operationson a metal plate. In one method of producing such a junction box orheader a flat inetal plate of required dimension is first pressed intochannel fori-u (see Fig. G of the drawings) and then by a `furtherpressing operation or operations the sides or walls of the channel arebent inwardly until they meet (see Fig. 'l' of the drawings) so toforina tubeor box of suitable cross-section; the meeting edges of theplate are preferably ehainfered to form a bed for the inetal depositedin the welding operation whereby the edges of the plate are securedtogether, 11h (Fig. 7 indicating the welding metal by which tho saidedges are united. The ends of the tube or box thus produced are thonclosed by end plates llc welded in place as shown in Fig. 8. 1n the topor upper wall of the junction box thus produced the necessary holes toreceive the ends of the down-flow and up-flow water circulatingl tubes12 and 12% arev formed, and the hereinbefore nieutioned openings 11"L(Figs. 2 and 9) are fornied in the bottoni or lower wall of the junctionbox. 1n the preferred construction' of the junction box as abovedescribed the welded or meeting edges of the metal of which the box isformeel are arranged or located in the wall of the box in which theaforesaid relatively large openings 11"1 are provided so that it is onlynecessary to connect or 'feld together the edges ofl those portions ofthe inetal plates which lie between or forni transverse bars or bridgesbetween the ends of adjacent openings 11n. ln these bars or bridgesholes or openings closed by screw plugs are formed to permit theentrancel of a tube expander for securing the ends of such of the watertubes 13 as lie opposite the said transverse bars or lli-idees, theseholes being` indicated by the reference uunierals 1S in Fig. 9 of thedrawings. Around the openings llu in the bottoni of the junction box arescrew studs 19 (Fig. 9) whereby the cover plates 15 are secured in placeso as to close the openings 11a.

2O and 21 3) are the holes respectirely in the bottoni of the waterdistributor 9 and in the top of the header or junction bot-1 ll in whichthe ends 1:2 and l2" respective-ry of the down-flow water tubes i2 arcexpanded, and 22, 22 are the h les in the top ot' the header or junctionbox 1l in which the lower or inlet ends of the upilow water-tube. ll areexpanded. n order to provide adequate bridges between the holes 22, 22in thetop of the junction box l1 these holes are arranged in twoparallel rows the holes 22 in the outer row being located opposite thebridges or portionsv of nietal between the holes 22 in the inner row andalso located. opposite the bridges or portions of metal between theholes 21 in which the ends '12" of the down-flow tubos l2 are expanded.rllhe said up-flow tubes 13 secured in the holes 22, 22 are, at a shortdistance above the top of the junction box l1, so bent that they lie ina Vertical plane intermediate the planes in which the two rows of holeslie, the tubes secured in the holes Q2 being bent outwardly towards theplates (3 forming the side or shell of the lire-box, and the tubessecured in the holes 22a bent inwardly towards the center of thefire-box, the tubes secured in the holes 22 being also bent in alongitudinal plane of the fire-box so that the niain portion of all theup-llow tubes 18 (i. e. those secured in the hole 22 and those securedin the hole 22") lie in the saine longitudinal plane of the lire-box andare evenly spaced apart.

In the alternative construction illustrated in Figs. 1S, 19 and 2O ofthe drawing parts corresponding to those above described with referenceto and shown in Figs. 1 to 17 of the drawings are indicated by the sainereference numbers as are applied to the parts in Figs. 1 to 17. In thealternative constructions shown in Figs. 1S, 19, instead of the waterdistributors 9 being made of two U- shaped pressings welded together ashereinbefore described with reference to Figs. 4 and 5 of the drawings,these distributors are each made from'a single piece of metal plateconstruction illust-rated in Figs. 18 and 19.

As shown in Fig. 17h. thejdrum 8 is ma-V chined or turned down aty eachend to provide a slight shoulder 8a which lies at the inner edge of theaperture in the tube-plate f 2a at thev front end of the iire-box,thehereinbefore described dished orV flanged Aplate 2 employed in theconstruction illustrated in Fig. 1 being omitted. As shown in Fig. 19the turned down or reduced end of the drum 8 projects slightly beyondthe t-ube-plate 2a. Similarly the ends of each of the water distributors9 are, as shown in Fig. 19, ma-

chined or turned down so as to provide a slight shoulder, the shoulder9a at one end of the distributor lying atthe inner-edge of the aperturein the said plate 2a and the corresponding shoulder o'f the opposite endklying at the inneredge of the. corresponding aperture inthe plate 5(Fig. l) at the rear or fire hole end of the re-box.

In assembling the various parts of the water-tube boiler equipment inthe tire-boxy when employing water distributors 9 constructed in themanner described with .referenceto Figs. 18, 19' and '20 ofthe drawings,these distributors are preferably so arranged ythat vrthenvveldedjointlldv (Fig. 20)-is adjacent to the plates 6 constituting the. shellor side walls of the fire-box. f

, As shown in Figsl and 18 the water distributors 9 are provided with asuitable number of transverse stays 23 these stays' being arranged sowasto liedirectly above the bridges between the ends of the down-t flowtubes 12 secured'- in the bottom of the distributors.

Referring now to Figs.` 21,22, 23 and 24 of the drawings, whichillustrate a modified construction of the r water-tube boiler orwater-tube equipment suitable either for -a locomotive boiler or amarine boiler and also suitable for use as either a stationary or aportable boiler or steam generator, the

differences between the constructions shownl in 'theseitigures and theconstructions hereinbetore described with reference to Figs. 1 to 2() ofthe drawings will be apparent but may be briefly described as followsThe headers or junction boxes 11 in the upper wall of which the lowerends of the hereinbeiore mentioned downtake or downtlow tubes 12 anduptake or up-low tubes 13 ,arefixed are in this instance each providedwith covers 154 of dish'or channel form in cross-section in the-slopingends of which covers screw plugs 15 (Fig. 21) `are pro-` vided wherebysediment, sludgeor matter carried vdown in the water and deposited inthe said junction boxes will settle inthe recesses formed in thedish-shape covers 15u and canbe readily cleared out by removing thescrew plugsv 15b and inserting the nozzle ot a water hose in the plughole. Further,

as will be seen Von reference to Fi'gf23, the f arrangement of. the endsofthe water up` take or up-'low tubes 13 in the top ofthe junction boxdiffers from that ,shown in Fig. 3, and a larger vnumber otl these tubes13 is provided, there being, as shown in Fig. 23, six otthese uptaketubes 13 to each downtalre tube 12-so that in this case the heatingsurface is largely increased as compared with that of theconstruction'illus-4 trated in Figs. 1, 2 andy 3. Further as shown` inFig. 21 the hereinbefore vmentioned dished or fiangedtube-plate 2 is inthis case secured inthe Jforward end of a tubular and more or lesstapering extension or, chamber 24 the rear end of which is secured inthe flange portion 5b of the inner plate 5a at the front end yof thellire-box.

bentv and welded as hereinbefore described with reference to Fig. 20;further, instead The kwater dise,v` tributors 9 in Figs. 21 and 22 maykeach be made from a single piece of plate metal of holes closed byscrew plugs, as shown in Fig. 18 of the drawings, being provided in theytop of the water distributor shown in Fig. 22 relatively large openingsmay be -formed in the top of each distributor and closed by cover plates14a which may be secured tothe top of, the distributor b screw studs andnuts. k f

Referring to Fig. 25 which illustrates a modified construction of there-box casing or shell, in this case it will be seenthat the rear endplate 5 of the lire-box, instead of extending to the bottom of thetire-box as in the constructions shown in Figs. 1 and 2, terminates at aposition above the fire-hole or re-doorvopening 30 and below the bottomofthe water distributor 9 which is arranged at afhigher level in thelire-box than are the distributors 9 shown in Figs. 1r and 21.r`Similarly the inner platea at the front end ot' the lire-box in Fig. 25terminates at a position a short distance below theflevel of the bottomof the boiler barrel instead ot', as in Figs. 1 and 21, extending to thebottom of the lire-box. 31

and 32 are lire-brick linings respectively at' and above described isparticularly suitable for marine, stationary y*and portable boilers.`r

In -Figs. 2 and 3, 25 is a strengthening or stiiiening plate ofapproximately U- shape in cross-section, the said plate being secured,for instance riveted, to the backplate et; as shown this plate 25extends a short distance into the adjacent end of the water distributorE). That portion o'f the plate 25 which lies in the water space betweenthe back plate d and the plate 5, as shown in the right-hand portion ofFig. 2, is of Vgreater depth or height'than the portion which extendslinto the water distribut-or 9 so that within the said water space theplate projects above the top and below the bottom oi the waterdistributor 9 as indicated 'by the reference numerals 25a 'in Figs. 2and 17a.

26, Figs. 1, 2 and 3 are water tubes situated lbelow the usual iire'archin the-lire- 'box these tubes being expanded at their opposite ends inholes respectively in the plate 5 at'the rear end oi` 'the lire-bor` andinthe inner -plate 5a Iat the front end ot the `nre-box. rlhese 'tubes26 lp'r'ovide 'for circulation of Water between the AWater spaces attheback and front o'lthe tire-box.

27, 271 (Figs. i, 2, is, li9, si andes) are longitudinal boilenstays,the stays 27 extending through the `water collector or water-receivingdrum 8 preferably close to the wall thereof, as shown inFig. 2v, thesaid stays being secured in place at the ends oi the :lire-boxpreferably by removable pins 28.

In thespaces between'the side plates'G oi' the lire-box and the ldowntake Water tubes 12 and water distributors 9 suitable heat insulatinglagging is proi'fided, 29 (Figs. 2 and'22) beingY'angleplates'coni-ining this lagging at the top of sthe said spaces.

Similar 1lagging maybe 'provided between the wrapper plates 16 and 'theinwardlybentupperportio'ns oi the up-low or Yrip-take V'water 'tubes 13.

It will be understood that vwater vtrom the L'water space in the barrelor body of the boilerilows into fthe water 'distributors 9 'andtherefrom down the outer rows ot downtlow tubes'12 into the'headers orjunction boxes 11 and thence through the uptake or upflo'w tubes 13 intothe aforesaid collector or water receiving'drum S, and that owing to theintense heat =to Vwhich the tubes 13 are subjected in 'the fire-box,fandto the weight of thelarge volume oit cooler water descending the outerrows of tubes 12, the circulation of the water is veryirapid, andliability of'burning'outot the'tubes and of lodgment of scale 'thereinis miniini'zed or prevented so that after prolonged use the tubes retaintheir original vhigh ericency for steam generation.

Further it will be understood that the hereinbeiore mentioned Waterdistributors sides of the 'lire-box casing and -forming I" rontand rearspaces `therein or'steamand water, a receiving drum y'having vits endssecured to the lire-box end plates and coinnunicating with the saidIliront and rear spaces, headers `arranged klongitudinally 'at the lowerApart of the sides of the Vlire-box and its casing, a series of `innerwater tubes connecting the said iheaders with the said receiving drumand iorming lwith 'the llatter the sides and topoitbefire-box,-waterdistributors arranged init-he spaces between theiire-'boxfandits'casing and havingtheir ends secured tolthe lire-bon end-platesandcommunicating with the said front 4and rrear spacesiindependently ofthe receiving drum and ot each other, and a-series ofouter water tubes connecting the sa-idvwate'r distributors andfheadersand'arranged inthe spacesbetween-the sides of the lire-boxfand .thesides oi'theiire-box casing.

2. A steam' generator asset tortlijin claim 1, the saidywater-distributors being oblong in cross-section and arrangedvertically iin fthe spacesfbetween the sidesof the fireiboX and thesides ot' the lire-box `casing below'the level of the bottom ot' thesaid receiving drum.

3. A steam generator'as set forth infclaim 1, and havingalso crownplates 'arranged above the upper end portions fot' 'the "said innertubes lbetween the -receiving druma'nd the water distributorsand-operating to-prevent leakage 'from thelireiboX casing into thelire-box beti'veen'the'tubesfat its top.

4. A steam generator assettortlrin claim 1, ythe said water distributorsbeing'spaced apart from the sides of the lire-box casing, and platesJfor supporting vheat-insulatiing lagging secured between theadjacent'sides o't the said water distributors andreasing in the upper'parts of thespac'esbetween them.

5. 'In a steam generator, aboiler barrel, a fire-box casing secured 'toland communieating with the boiler barrel, lire-box 'end plates securedin'the front and rea'rendv portions of the lire-boi; casing and formingwater spaces therein, tubular waterdistributors having theirend portionssecured directly to the tire-box end plates and'arrangedlongitudinally'between the sides of the tire box and the sides ofthefire-box'casing and communicating with the water spaces attheir-ends, a receiving'druin arranged longitudinally in the fire-boxcasing-above and between the water distributors and `coiniii()municating with the upper part of the space in the boiler shell, headersarranged longitudinally below the Water distributors, a series of outerWater tubes connecting the Water distributors withl the headers at eachside of the nre-box casing, and a serie-s of inner Water tubesconnecting'the headers with the said receiving drum, the said endplates, inner tubes and receiving drum forming the lire-box inside thelire-box casing.

6. In a steam generator, a {ire-box casing, lire-box end plates secured1n theiire-box casing and forming with it parts of a space which is aportion of the steam and Water space of the generator, a receiving drumhaving its ends secured to the fire-box vend plates and communicatingwith the saidV space, a header arrangedlongitudinally at the lower partof the sides of the fire-box and its casing, a series of inner Watertubes connecting the said header With the said re-yk ceivlng drum andformlng With the latter one side of the lire-box an-d a portion of itstop, a Water distributor supported in the said space between thefire-box and its casing and communicating with the said spaceindependently of the receivingdrum,v and a series of outer Water tubesconnecting` the said Water distributor and header and also arranged inthe said space between the sides of the iirefbox and its casing.

7. A steam generator as set forth in claim 5 and having also stideningplates U-shaped in cross-section said plates being secured with theirclosed ends against the rear end plate of 'the nre-box casing With theirfree end portions arranged vertically and projecting Within the rear endportions of the said Water distributors. a

In testimony whereof' We aiiiX our signatures.

ROBERT AB'sALoM rHoM. JAMES THoM. y

